How can someone find textless covers from before the late 2000s? I have been lucky with some TPBs that happen to include them but is there a good repository for one-shots or annuals from this time period? I'm having a really hard time finding many of them, e.g every DC One Million issue.
Highly unlikely that you'll find such a source. None of the covers for that era were created as textless first, like they do nowadays. All textless versions of 90s covers (or earlier) are actually remastered versions by DC. Basically they digitally remove the letters and/or logos from the images and reuse the images for new publications.
So it all boils down to luck. If DC has reissued the cover, then there's bound to be a textless versions somewhere around. Otherwise, it's a fool's errand.
Hm. That's funny. I've managed to come across several which seem almost random from search engines (see my recent uploads) but it's confounding what is out there and what isn't--e.g. all but issue six from JLA Incarnations (Volume 1). Why?